FYI: transforms_top_down not to be used in caravana or similar masking problem

Part 1 (2018)
1

Just an FYI:

I was working on the nucleii dataset from datasciencebowl2018.
I innocently chose transforms_top_down as the augmentation since it seemed natural.
the results were disastrous. the masks were no longer matching images.

<+++++++++++++++++++Update++++++++++++++++++>
I tried re-constructed transforms_top_down (for the nucleii dataset from datasciencebowl2018) as:

aug_tfms = [RandomRotate(10, tfm_y=TfmType.CLASS),
RandomLighting(0.05, 0.05),
RandomDihedral(tfm_y=TfmType.CLASS)]

That works just fine.
So don’t use transforms_top_down as is and you can not specify it as:

transforms_top_down( tfm_y=TfmType.CLASS)

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2

I do plan to add that functionality soon FYI. :slight_smile:

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Thank you @jeremy,
I am now addicted to fastai.
First thing in the morning I check updates in MOOC lectures and updates in the repository even before checking news!
Thank you for making a difficult subject so interesting!

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